Finally, Bilbo and the dwarfs reach the Lonely Mountain. Inside lives the dragon, Smaug, and he will kill them if he catches them. After days of searching, Bilbo discovers the secret entrance, and they move inside.
Because he was so helpful, strong and brave on the quest, the dwarfs nominate Bilbo to go into the dragon's lair and take the first piece of well-earned treasure. While he's near the dragon, Bilbo discovers that Smaug has a weak spot on his underside - the one way to take him down.
Word of Smaug's weakness reaches a nearby village via a bird that was listening to Bilbo. A villager shoots an arrow into Smaug's weak place, and the dragon falls to his death. After the dragon is dead, there is much arguing about who gets the treasure. The dwarfs want to keep it themselves, but the village needs some after Smaug destroyed their homes. A brutal war brakes out, and many die. But, in the end, an agreement is settled upon, and Bilbo's adventure is complete. He heads home, a new side of himself revealed. And he likes it.